Rust-preventive compositions



Patented Oct. 24, 1950 2,527,296 RUST-PREVENTIVE COMPOSITIONS J ohrr W.Bishop, Plainfield, N. J assignmto Tide Water Associated Oil Company,Bayonne, N. J a corporation of Delaware No Drawing. Application April21, 1948,

- Serial No. 22,503

14 Claims.

The present applicationis a continuation-inpart of my co-pendingapplication. Serial No. 607,677, filed July 28, 1945, now U. S. PatentNo.

2,442,581, issued June 1, 1948, entitled Rust-Pre ventive Compositions.

In the aforesaid co-pendingapplication, compositions are disclosed thatare adapted for use in the prevention of rusting of metals, particularlyferrous metals, upon exposure to humid atmospheres and other atmospheresconducive to rusting of metals. Briefly, the compositions disclosed inthe aforesaid co-pending application comprise a suitable liquid vehiclein major proportion having dissolved therein a minor, butrust-inhibiting amount, of a salt formed by an acid ester of aphosphorus acid with an oxazoline compound. The present inventionrelates to compositions similar thereto but which, in addition,essentially contain a suitable metal sulfonate, the presence of such asulfonate in combination with the aforesaid oxazoline salt having beenfound to provide a degree of rust-inhibiting characteristics many moretimes effective than would normally be expected from a summation of theindividual effectiveness of the oxazoline salt or the metal sulfonate.

Broadly speaking, the compositions of this invention comprise a majorproportion of a suitable liquid vehicle having dissolved therein a minoramount, sufiicient to substantially inhibit rusting, of arust-inhibiting agent comprising a metal sulfonate and a salt formed byan acid ester of a phosphorus acid with an oxazoline compound. Ingeneral, vehicles suitable for practicing the invention comprise organicliquids that are solvents for the metal sulionates and the oxazolinesalts embodied herein, and, additionally, are not per se effective tosubstantially induce corrosion of metal surfaces when applied thereto.In preferred embodiment, the vehicles employed are relatively non-dryingorganic liquids that have the aforesaid solvent characteristics and aresubstantially inert with respect to enhancing the rusting of metals uponexposure to atmospheres conductive thereto. In a still morepreferredembodiment, liquid hydrocarbons are employed as vehicles forthe rust-inhibiting agents of this invention. Illustrative thereof aremineral oils, fractions thereof, naphtha, aromatic solvents such as, V.M. and P. naphtha, benzol, and the like.

With reference to the salts embodied herein as a component of therust-inhibiting agent, such salts may be prepared by subjecting toaddition reaction conditions a blend comprising an oxazo- 2 linecompound and an acid ester of a phosphorus acid. With respect to theoxazoline compounds suitable for preparing such salts, particularlyeffective types are the compounds known to the art as 2-oxazolines whichcontain the following It is preferred to employ such oxazoline compoundsin which one or more of the ring carbon atoms carries a long chain alkylgroup, i. e., a long chain saturated or unsaturated hydrocarbon radical.More preferably, such oxazoline compounds are employed in which at leastone of the ring carbon atoms carries an aliphatic group containing fromabout 4 to about carbon atoms, as for example, such as may be obtained athe hydrocarbon residue from an acid of the fatty acid series. Althoughthe invention contemplates use of such oxazoline compounds in which along chain alkyl group is carried by any of the ring carbon atoms, in astill more preferred embodiment, oxazoline compounds are employed thatcarry a long chain alkyl group on the carbon atom between the nitrogenatom and the oxygen atom in the oxazoline ring.. More specificillustrations of such compounds may be represented by the followingstructural formula:

wherein R, R1, and R2 may be hydrogen or alkyl and R is alkyl and, moredesirably, R. is of such chain length as may be obtained as the alkylesidue from a higher fatty acid as for example. lauric acid, oleic acid,stearic acid, and the like. Examples thereof are the oxazoline compoundsproduced by reacting oleic acid with Z-aminoz-methyl-l-propanol andhaving the following formula:

CH: I CH:

O Ou t and the reaction product of oieic' acid and z-amino-l-butanol orz-nitro-l-butanol having the following formula:

Quin

Other oxazolines which may be suitable and methods for their preparationare known. as for example, as displosed in U. 8. Patents Nos. 2,372,-409 and 2,372,410.

The acid esters suitable for reaction with the oxazolines to prepare theaddition compounds employed as a component of the novel compositions maybroadly be defined as partially esterifled inorganic acids ofphosphorus. In preferred em- 7 at least one hydrocarbon group havingabout 4 to about 22 carbon atoms. More specific illustrations thereofare the monoesters of orthophosphoric acid, such as monooctyl acidphosphate. monolauryl acid phosphate, monooctadecyl acid phosphate, andthe like, and di esters, such as dioctyl acid phosphate. di-2-ethylhexyl acid phosphate, dilauryl acid phosphate, dioctadecyl acidphosphate, and mixtures of such acid monoand di-alkyl esters. Stillfurther illustrations of suitable esters include acid esters ofphosphoric acid that contain an aryl and/or an alkyl-substituted arylradical, as for example, as may be illustrated by esters such as themonoand dicardanyl acid esters of phosphoric acid.

As aforesaid, the rust-inhibiting agent embodied herein comprises asuitable metal sulfonate in combination with an oxa'zoline'salt asaforedescribed. Such metal sulfonates desirably consist of alkali oralkaline earth sulfonates, such for example, as those derived frompetroleum mahogany acids. One particularly eifective compound of thelatter type is sodium sulfonate, a composition of which is known in theart as Petronate," containing about 60 to 65% of sodium sulfonatedissolved in a mineral oil.

In practicing this invention, various methods may be employed forpreparing the novel rustinhibiting compositions. One method is toprepare the oxazoline salt of an acid ester of a phosphorus acid, andincorporate the salt and the metal sulfonate into the solvent vehicle.Another method is to separately add the acid ester and the oxazolinecompound to the oil whereupon these two substances react in the oil atroom temperature to form, in solution, the addition 4 desiredcombination of the acid ester with the oxazoline compound. m

As aforesaid, the active rust-inhibiting materials generally comprise aminor proportion by weight of the compositions of this invention and,for most usages, the total concentration of the oxazoline salt and thesulfonate need not exceed about 10% by weight of the composition.Although amounts exceeding 10%, as for example. up to about 20%, of therust-inhibiting ingredients may be employed, in most instances, suchlarge amounts are unnecessary as smaller proportions are highlyeffective. Thus, in practicing the invention, the oxazoline salt may beemployed in amounts ranging from about 0.1% to 10% and the metalsulfonate in amounts ranging from 0.5 to 15% based on the weight of thecomposition. However, for most purposes and in preferred embodiment, theoxazoline compound is employed in amounts ranging from about 0.25% to 3%and the metal sulfonate in amounts ranging from about 1% to 8%.

The oxazoline compounds, when used individually, have relatively little,if any, eflectiveness in the inhibition of rusting of steel surfaces.Similarly, acid esters of phosphoric acid, if taken alone, are onlymoderately, if at all, effective in this respect. However, the oxazolinesalts of such acid esters exhibit a degree of rust-inhibitingcharacteristics considerably in excess of the summation of theindividual effectiveness, if any, of the individual components of theoxazoline salt. Moreover,-and as is known to those skilled productthereof. When the salt is thus formed,

the metal sulfonate is added to the oil.. when the latter method isemployed for preparation of the rust-inhibiting compositions, it ispreferred that the salt be formed in the vehicle prior to addition ofthe sulfonate in order to avoid the tendency of the acid ester to reactwith the sulfonate which would result in removal of acid ester from thereaction mixture, thus preventing the in the art, metal sulfonates suchas the sodium salts of mahogany acids exhibit a certain degree ofrust-inhibiting characteristics when applied to metals. However, as isevidenced by the data set forth hereinafter, use of a metal sulfonate incombination with an oxazoline salt, as aforedescribed, provides a degreeof rust-inhibiting characteristics that is many more times eflectivethan would be expected from a summation of the individual effectivenessof the oxazoline salt or the metal sulfonate when either of thesematerials is used individually in a concentration equivalent to use of acombination of the oxazoline salt with the metal sulfonate. The use ofthe metal sulfonate in combination with the oxazoline salt not onlypermits use of considerably less amounts of the oxazoline salt to obtaina high degree of rust inhibition, but use of such a combination resultsin considerable economics as the metal sulfonates are relativelyinexpensive as compared to the oxazoline salts. A further, and importantfeature lies in the fact that these compositions form stable solutions.Obtainment of solution stability, as well as rust-inhibitingeflectiveness, in compositions containing complex additives, constitutesa major problem in the art. The present discovery of components havingcompatible solubility characteristics, while at the same time exhibitinghighly eflective rust-inhibiting characteristics and other desiredproperties, is a major advance in the art.

Although the exact reasons underlying the highly effectiverust-inhibiting characteristics obtained by practicing this inventionare not fully known, it is believed that such results are apparentlycaused by co-action or interdependence between the additive components.The additive materials are highly polar in character which may accountat least in part for the powerful rustpreventive properties. Presumably,this polar structure is also responsible for an additional desiredcharacteristic possessed by these composi- I here tenaciously to metalsurfaces but provide protection thereof under a wide variety of adverseconditions as is apparent from the tests disclosed hereinbelow. Anadditional desired characteristic of the compositions disclosed hereinis that they are not readily removable by water from metal surfaces towhich the been applied. y

In order to further describe the invention, the following example setsforth an illustrative embodiment of the highly effective rust-preventivecharacteristics provided by use of compositions such as embodied herein.In the example, the rust-preventive characteristics of the compositionsdescribed were determined by subjecting the compositions to the severerust-inducing conditions of the humidity corrosion test described in"Army-Navy Aeronautical Specification Compound: Corrosion-Preventive;Air Craft Engine" AN-VV-C-576b. In accordance with the test, two

compositions have 0 conditions of the aforesaid humidity test. severalcompositions, as described in the following examples, were prepared andsubjected to test in accordance with the test described in USA'2-122Oil, Lubricating, Preservative, Medium. Briefly,

the test comprises immersing freshly sand-blasted steel panels in theoil under test at room temperature for one minute, draining the panelsat 130 F. for 16 hours, and placing the panels in a special humiditycabinet maintained at 95-100% relative humidity at 100 F. The testcomposition is considered as passing the test if, at the end of 300hours, corrosion has not occurred within V from any edge of the panels.

Example I! of lauryl acid phosphates and 0.4% of an oxafreshlysand-blasted steel panels are coated on all surfaces with the test oil,drained for at least four hours in an atmosphere of to relative humidityat 25 C., and then subjected to a circulating atmosphere of 95 to 100%relative humidity at a temperature of 120 F. for 150 hours in a specialhumidity cabinet. At the end of the test period, the panels are removedfrom the humidity cabinet, cleaned with naphtha, and examined. Thepresence of any corrosion on the panels except within from any edge,evidences failure of the test composition.

Example I A composition was prepared by dissolving in a mineral oil ofSAE 40 grade 3% by weight of sodium sulfonate and 1% by weight of theaddition salt formed by lauryl acid phosphates with an alkyl-substitutedoxazoline prepared by reaction of oleic acid with2-amino-2-methyl-l-propanol. Thus, the active rust-inhibiting agent waspresent in a total amount of 4% based on the weight of the oil. Whensubjected to the aforesaid humidity test, the metal panels wereprotected against rusting for more than 450 hours.

For purposes of comparison, and in order to illustrate the unexpectedhigh degree of rustinhibiting characteristics provided by use of thevided by the composition containing only the sulfon'ate was about 65hours, and, by the composition containing only the oxaaoline salt, about150.. 200 hours.

In order to further describe the invention, and to illustrate theexcellent rust-inhibiting characteristics provided by practicing thisinvention under rust-inducing conditions diiferlng from the zolinecompound formed by reaction of oleic acid with2-amlno-2-methyl-1-propano1, and stirring the blend until a homogeneoussolution was obtained. Thereupon, .5% of Petronate sodium sulfonate) wasdissolved in the solution, thus providing a total additive concentrationof about 2.4%. This composition, upon being subjected to the aforesaidhumidity test (USA 2-122) protected the metal panels against rusting forat least 300 hours.

Example III To a petroleum lubricating oil consisting of a blend of 50%solvent refined, acid treated, wax

to the aforesaid humidity test, the protection profree neutral oil of 60SUS at F. derived from coastal crude and 50% non-viscous mid-continentsolvent treated neutral of 858138 at 100 F., there were added 0.75% ofdilauryl acid phosphate and 0.6% of the oleic acid2-amino-2-methyl-lpropanol reaction product as aforedescribed. When thesolution had become homogeneous, 8% of "Petronate" was added to anddissolved in the oil composition. When tested under the condition of theaforesaid humidity test at 100 F., this composition passed therequirements thereof, and also satisfactorily passed the salt water testset forth in the aforesaid USA specification 2-122 and the salt spraytest set forth in Specification O. S. 1362. Briefly, the salt water testcomprises totally immersing two sand-blasted steel panels in the testoil, draining the panels for 16 hours, and then totally immersing thepanels for 20 hours in synthetic sea water. The test panels, after beingremoved from the sea water and dipped in acetone, must show nocorrosion, except within M; inch from any edge, if the test oil is to beconsidered as having passed the test. The salt spray test comprisesdipping three test panels of freshly sand-blasted steel in the test oil,draining the same overnight at room temperature, then exposing thepanels at room temperature'to a fine mist of 4% aqueous sodium chloridesolution for 24 hours. Any corrosion on the panel surfaces, exceptwithin inch from any edge, indicates failure of the test oil to protectagainst rusting under the test conditions.

Example IV In a manner similar to that set forth in Example III,compositions were prepared by dissolving in an SAE 30 grade 011, a totalof 2.4% by weight of a combination additive comprising sodium sulfonate,the aforesaid reaction product of oleic acid with2-amino-2-methyl-l-propanol, and lauryl acid phosphates in proportionsas set forth in the following tabulation. when subiected to theconditions of the aioredescribed humidity test, the compositionscontaining the combination additive protected the metal panels againstrusting for at least 360 hours, as is set forth in the tabulation. Sucha high degree of rust-preventive characteristics is completelyunexpected irom a summation of the individual etfectiveness of thecomponents of the combination additive as compositions based on the sameoil containing only sodium sulionate in 2.4% concentration or only theaforesaid phosphate and oxazoline compound in a total concentration of2.4% in the same proportion as in the examples in the tabulation, failedin 216 hours or less when subjected to the humidity test.

Total Additive Concen- SAE 30 tration Grade Oil Sodium Sulionate AcidEster Oxazollne Compound Although the present invention has beendescribed in conjunction with certain preferred embodiments thereof,those skilled in the art will readily recognize that variations andmodifications can be' made. Such modifications and variations are to beconsidered to be within the purview of the specification and scope ofthe appended claims.

I claim:

1. A rust-preventive composition comprising a liquid hydrocarbon havingdissolved therein (a) about 0.1 to about by weight of said compositionof a rust-inhibiting salt formed by an acid ester of phosphoric acidcontaining ahydrocarbon group of about 4 to 30 carbon atoms with anoxazoline compound containing an aliphatic group of about 4 to 30 carbonatoms and (b) an oil-soluble rust-inhibiting metal sulfonate from thegroup'consisting of alkali and alkaline earth metal sulfonates in anamount of about 0.5 to based on the weight of said compositionsuflieient to impart to said composition rust-preventive characteristicsin excess of the sum of the individual efiectiveness oi the salt andsulfonate.

2. A composition, as defined in claim 1, wherein the liquid hydrocarbonis a mineral oil.

3. A composition, as defined in claim 1, wherein the salt is present inan amount of' about 0.25 to about 3% and the sulionate in an amount oiabout 1 to about 8%. v

4. A composition, as defined in claim 1, wherein the acid phosphate isan alkyl acid phosphate.

5. A composition, as defined in claim 1, wherein the acid phosphate islauryl acid phosphate.

6. A composition, as defined in claim 1, wherein the oxazoline compoundis a 2-oxazoline in which a ring carbon atom is directly attached to thehydrocarbon residue of a fatty acid of about 4 to carbon atoms.

7. A composition, as defined in claim 6, wherein the hydrocarbon residuedirectly attached to a ring carbon atom in the oxazoline is thehydrocarbon residue of oleic acid.

8. A composition, as defined in claiml, wherein the metal sulionate isderived from a petroleum mahogany acid.

9. A composition, as defined in claim 1, wherein the metal sulionate isa sodium salt of petroleum mahogany acids.

10., A rust-preventive composition comprising a mineral oil havingdissolved therein (a) about 0.1 to about 10% by weight of saidcomposition oi. a rust-inhibiting salt formed by an acid ester ofphosphoric acid containing a hydrocarbon group 'or about 4 to 30 carbonatoms with an oxazoline compound containing an aliphatic group of about4 to 30 carbon atoms and (b) an oil-soluble rust-inhibiting alkali metalsalt of a petroleum mahogany acid in an amount of about 0.5 to 15% basedon the weight of said composition suflicient to impart to saidcomposition rust-preventive characteristics. in excess of the sum of theindividualeflectiveness of the salt and sulfonate.

11. A rust-preventive composition comprising a mineral oil havingdissolved therein, by weight of said composition, about 3% of a sodiumsalt of petroleum mahogany acids and about 1% of a salt formed by laurylacid phosphate with a 2-oxazoline containing the hydrocarbon residue ofoleic acid.

12. A composition comprising a mineral oil having dissolved therein, byweight of said composition, about 1.5% of a sodium salt of petroleummahogany acids and about 0.9% of a salt formed by lauryl acid phosphatewith a 2-oxazoline containing the hydrocarbon residue of oleic acid.

13. A composition comprising a mineral oil having dissolved therein, byweight of said composition, about 5% et a sodium salt of petroleummahogany acids and about 1.3% of a salt formed by lauryl acid phosphatewith a 2-oxazoline containing the hydrocarbon residue of oleic acid.

14. A composition comprising a mineral oil having dissolved therein, byweight of said composition, about 1.8% of a sodium salt of petroleummahogany acids and about 0.6% of a salt formed by lauryl acid phosphatewith a 2-oxazoline containing the hydrocarbon residue of oleic acid.

. JOHN W. BISHOP.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. A RUST-PREVENTIVE COMPOSITION COMPRISING A LIQUID HYDROCARBON HAVINGDISSOLVED THEREIN (A) ABOUT 0.1 TO ABOUT 10% BY WEIGHT OF SIADCOMPOSITION OF A RUST-INHIBITING SALT FORMED BY AN ACID ESTER OFPHOSPHORIC ACID CONTAINING A HYDROCARBON GROUP OF ABOUT 4 TO 30 CARBONATOMS WITH AN OXAZOLINE COMPOUND CONTAINING AN ALIPHATIC GROUP OF ABOUT4 TO 30 CARBON ATOMS AND (B) AN OIL-SOLUBLE RUST-INHIBITING METALSULFONATE FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METALSULFONATES IN AN AMOUNT OF ABOUT 0.5 TO 15% BASED ON THE WEIGHT OF SAIDCOMPOSITION SUFFICIENT TO IMPART TO SAID COMPOSITION RUST-PREVENTIVECHARACTERISTICS IN EXCESS OF THE SUM OF THE INDIVIDUAL EFFECTIVENESS OFTHE SALT AND SULFONATE.